Air flow control means for an air conditioning unit



Nov. 14, 1961 c. G. ALT 3,008,309

AIR FLOW CONTROL MEANS FOR AN AIR CONDITIONING UNIT Filed Sept. 30, 1960 FIG. I

FIG. 2

INVENTOR.

CARL G. ALT

ATTORNEY.

nected in such order. housing divides the housing into an evaporator compartment in communication with the area to be conditioned .United States Patent 3,008,309 AIR FLOW CONTROL MEANS FOR AN 1 AIR CONDITIONING UNIT Carl G Alt, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Sept. 30, 1960, Ser. No. 59,673

Claims. (Cl. 62-429) This invention relates to an air conditioning unit of the self-contained type and more particularly to a self-conair conditioning unit having improved means for dr ving the evaporator fan and the condenser fan in such Unit.

A typical air conditioning unit in common domestic use comprises a refrigeration system mounted within a casing. A partition in the casing divides the interior thereof into a condenser compartment and an evaporator compartment. The unit is oriented in a window or like opening in a room so that the evaporator is in communication with the area to be conditioned and the condenser faces the ambient. Fan means are provided adjacent the evaporator to circulate room air over the evaporator; similar fan means are provided adjacent the condenser to circulate outside air over the condenser.

In the past, a separate electric motor has been used to drive each fan means at difierent rates of speed for it is well known that for efficient operation of the refrigeration system of the air conditioning unit, more air must be passed in heat exchange relation with the condenser than with the evaporator. More recently, for reasons of economy, a single fan motor having oppositely extending shaft ends, to each of which is secured a fan means, has been used to drive both fan means simultaneously. The motor selected for this purpose must drive the fan means at a speed sufficient to move an'adequate volume of air over thecondenser. As the volume of air required over the evaporator is substantially less than required over the condenser, the evaporator fanrotates at an unnecessarily high speed causing excessive noise and resulting in inefiicient cooling performance. 'The noise is particularly undesirable forthe evaporator is in communication with the room to be cooled and the noises emanating from within the evaporator chamber may be readily heard by the user of the air conditioning unit.

A primary object of this invention is to provide an improved air conditioning unit wherein the deficiencies and disadvantages of prior units as outlined above are obviated.- I 1 Another object of this invention is to provide an air conditioning unit with novel drive means for driving the evaporator fan at a lesser speed than the condenser fan. Another object of this invention is to provide an air conditioning unit having an improved fluid transmission between the drive shaft mounting the condenser fan, and

.the evaporator fan, permitting the fans to rotate at differ- .ent rates of speed.

Y Still another object of the invention is to provide an- This invention relates to an air conditioning unit having a housing within which is disposed a refrigeration system. The refrigeration system comprises a compressor, a condenser, expansion means and an evaporator con- A partition mounted within the and a condenser compartment in communication with the outdoors. First fan means are provided for circulating over the condenser; second fan means are provided for a motor having a drive shaft extending beyond opposite ends thereof, the first fan means being secured to one of the shaft ends and fluid coupling means connecting the second fan means to the other shaft end, the second fan means rotating at a speed less than the speed of rotation of the first fan means.

The above and other objects of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown and wherein like numerals refer to like elements.

In the drawings,

FIGURE 1 is a horizontal sectional view somewhat diagrammatic of a self-contained type air conditioning unit embodying the present invention;

FIGURE 2 is a vertical sectional view taken through the assembled fluid coupling means; and

FIGURE 3 is a view partly in elevation and partly in section of a portion of the fluid coupling means of the present invention.

In FIGURE 1, I have illustrated a self-contained air conditioning unit of the type commonly referred to as a room cooler. The casing 4 of the air conditioning unit 2 is adapted to be supported directly on the window sill in accordance with well-known practice. The casing is provided with a partition 6 which separates the casing into a condenser compartment 8 and an evaporator compartment 10. The condenser compartment is adapted to face the outdoors. Condenser 12 extends substantially across one side of the casing 4. Within the condenser compartment 8 is disposed the compressor 14 which may be of the conventional hermetic type. The compressor 14 is adapted to discharge compressed gaseous refrigerant into the discharge line 18 from which it flows to the condenser 12. From the condenser the refrigerant flows through expansion means, which may be of the capillary tube type 20 as illustrated, to the evaporator 16. The refrigerant then flows back through the suction line 22 to the compressor 14.

A fan motor 24 is suitably secured to casing'4 within condenser compartment 8. A drive shaft having opposite ends 26 and 28 extends from motor 24. To one end of the drive shaft is fixedly secured a condenser fan 30. The evaporator fan 34 is connected to the shaft end 28 by means of fluid coupling 32. Fan 30 draws air over one half of the condenser through shroud 31 and out over the other half of the condenser to condense the refrigerant flowing through condenser 12. Evaporator fan 34 draws room air in through inlets 33 in the sides of easing 4 and discharges the air through the orifice 35 in shroud 37' over the evaporator 16 to cool the air prior to passage back to the room.

It is well-known that the volume of air necessary to adequately condense the refrigerant flowing through a condenser of a system of predetermined capacity is considerably greater than the volume of air circulating over the evaporator. Accordingly, I sought to provide a coupling means between the drive shaft andthe evaporator fan wherein the evaporator fan might rotate at a lesser rate of speed than the drive shaft and wherein the noise emanating from within the evaporator compartment of the air conditioning unit might be substantially reduced.

Referring now to FIGURE 2, I have shown a preferred form of coupling means to accomplish the desired end. The coupling means are of the fluid type and are generally comprised of a sleeve 36 adapted to be secured to shaft end 28, a member 38 rotatably mounted on the sleeve, a housing 40 adapted to be secured to the member 38 and likewise rotatably mounted on the sleeve and an impeller 42 adapted to be secured to the sleeve.

Sleeve 36 includes a collar 44 having therein atapped bore 46 for receiving a set screw 43 to connect the collar and therefore the sleeve to the shaft end 28. The sleeve 36 includes a bearing portion 50 upon which the member 38 ismounted, and a seat portion 52 to which the impeller 42 is rigidly secured and a bearing portion 54* for rotatably supporting the housing 40.

The impeller 42 has a hub 56' thereon. A tapped bore 58' extending through the hub receives a set screw 60 which fixedly secures the impellerto the sleeve 35.

The housing 49 and the member 38, which are rotatably mounted on the sleeve, are secured to one another by screws 62 which extend through openings ,64 (FIG- URE 3) in the member and engage in threaded bores 66 in the housing.

The housing and the member cooperate to define an annular chamber '68 about the sleeve; The impeller is disposed within the chamber 68. The chamber may be filled with a fluid of predetermined viscosity through fill hole 69, which is closed by means 70, preferably a plug. O-rings 78 and 89 are provided to prevent leakage of the fluid from within the chamber 68. A channel ring seal or the like may be used place of each O-ring.

It is to be noted that the facing surfaces 72 and 74 on the impeller and member, respectively, are provided with hemispheroidal depressions 76 and 77. These depressions lie in a circle generally the same radius from the axis of rotation of the shaft. As the impeller rotates, fluid flows into the generally spheroidal openings defined when the depressions in the mating surfaces align with one another and as the impeller and member move out of such alignment there is friction created in the oil which causes the member to rotate. At'start up, the housing 40 and fan 34 secured thereto by suitable means, as for example, set screw 41, are at rest. As the drive shaft 28 picks up speed, the rotation of housing 40 will increase. n

The rate of slippage between the impeller and the member may be changed by varying the volume of fluid in the chamber 68. A preferred manner of controlling the difference in speeds between the shaft and the evaporator fan is to use fluids of predetermined viscosity. The greater the viscosity of the fluid used in chamber 68, the smaller will be the difference betweenthe speed of the shaft and the evaporator fan.

The fluid coupling fordriving the evaporator fan is of: simple design and can be fabricated inexpensively. The preferred material for the housing, member, impeller, and sleeve is polytetraethylene, which has good bearing properties and is chemically resistant. Other plastics having similar characteristics may be used. The components may be formed of metal, in which case appropriate sleeve'bearings wouldbe required between the rotating surfaces of the components. 7

The arrangement for driving the evaporator fan provides for substantially noiseless operation and provides for maximum cooling efiiciency of air passing over the evaporator.

Operation 7 Considering now the operation of the air condition ing unit embodying the present invention, refrigerant vapor is compressed by compressor 14 and discharged into line 18 for circulation through the refrigenant circuit. The refrigerant is condensed in condenser 12, and

the flow of refrigerant to the evaporator 16 from condenser 12 is metered by capillary tube 20. In the evaporator, the refrigerant is vaporized, thereby extracting heat from th room air circulated over the evaporator.

motor 24 is energized to drive the fans 36 and 34. Condenser fan 30 is connected directly to the motor shaft and therefore rotates at the same speed as the shaft to supply an adequate rate of flow of air over the condenser 12. Evaporator fan 34 is connected to housing 40 of fluid coupling 32. The impeller 42 drives the member and housing 40 connected thereto through 4 the fluid in chamber 68 at a lesser speed than the speed of rotation of the shaft 28. As a consequence the air flow over the condenser and over the evaporator are optimized and the result is maximum operating efliciency of the refrigeration system. Too, the noise heard in the room by the user is substantially less than from prior arrangements.

Another advantage of the present invention is that at start up only the condenser fan 30 is connected to the motor 24. The starting torque required by the fan motor is reduced and this in turn reduces the starting current required by the fan motor. The fan 30 rotates at almost its desired or rated speed before the evaporator shaft commences rotation. Thus, the load on the shaft imposed by the fan becomes a factor after the shaft has obtained its rated speed.

By virtue of the fluid coupling 32 employed in the air conditioning unit of the present invention, the speed of the evaporator fan is, in effect, independentof the speed of rotation of the'drive shaft but rather is a function of the viscosity of the fluid employed in chamber 68 or the volume of the fluid in chamber 68. By employing a fluid of a greater or lesser viscosity the speed of the evaporator fan can be easily controlled. T 0: supply fluid to chamber 68 a fill hole 69 may be provided in the housing 40.

While I have described andillustrated a preferred embodiment of my invention, it will be understood that my invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1; In an air conditioning'unit, a refrigeration system comprising a compressona condenser, expansion means and'an. evaporator connected in such order and means for passing air over said condenser and over said'evaporator comprising a motor having a drive shaft, a condenser fan secured to the drive shaft for rotation at the speed of the drive shaft, an evaporator fan, and fluid coupling means for connecting the evaporator fan to the drive shaft so that the evaporator fanrotates at a different speed from the speed of the drive shaft, said fluidcoupling means comprising aihousing loosely mounted on the drive shaft, said housing having an interval surface defining an annular chamber about'said drive shaft, a portion of said surfacelying in a plane perpendicular to the axis of said drive shaft, an impeller secured to said drive shaft within said chamber, said impeller having a surface adjacent to and parallel with said portion of said housing surface, each of said surfaces having depressions therein of generally hemispherical configuration, said chamber containing a fluid of predetermined viscosity and sealing means for retaining the fluid within said chamber wherebyfluid within the chamber is forced intothe depressionson the facing surfaces causing the housing and the evaporator fan secured theretoto rotate withbut at a lower speed of rotation than the drive shaft.

' 2. In an air conditioning unit, a housing a refrigeration system within said housing, comprising a. compressor, "a condenser, "expansion means, and an evaporator connected in such order, a partition .within' said housing dividing said housing into an evaporator compartment and a "condenser compartment, first. fanmeans for circulating air over said condenser, second fanmeans forcirculatling air'over said evaporator and drive meansfor rotating the first and second fan means at different rates of speed,

said drive means comprising a motor having a drive shaft ,at a speed less than the speed of rotation'of the'firstfan ,means,

13. .An air conditioning unit as iniclairn 2 wherein" said fluid coupling means, comprises a sleevesecured to the other of said'shaft' ends, an impeller secured to said sleeve, and means on said sleeve operatively connected to and driven by said impeller, said second fan means being fixedly secured to said means on said sleeve.

4. An air conditioning unit as in claim 3 wherein said means on said sleeve comprises a member rotatably mounted on said sleeve, a housing rotatably mounted on said sleeve and secured to said member, said housing and said member defining a chamber enclosing said im- 5. An air conditioning unit as in claim 4 wherein said member and said impeller have facing surfaces, said surfaces each having at least one depression therein, each of said depressions lying at substantially the same distance 5 from the axis of rotation of the drive shaft.

References Cited in the file of this patent UNITED STATES PATENTS Dickey Oct. 24, 1944 2,777,292 Mazzola June 15, 1957 

